Coating material with biocide microcapsules

ABSTRACT

The invention relates to a coating material for protection against microorganism invasion on surfaces which are exposed to the effects of damp or water. The coating material has either a pH-value of at least 11.0 or is provide with a base material for the coating whereby the pH-value is at least 11. The coating material is characterized in that it contains a biocide which bonds to solid particles in a carrier material and is released in a delayed manner therefrom.

The invention relates to a coating material for protection againstmicroorganism infestation on surfaces which are exposed to the effectsof damp or water, said coating material either itself having a pH of atleast 11.0 or being intended for the coating of a substrate materialwhose pH is at least 11.0. The invention pertains in particular toplasters and paints which are to be protected with biocides againstattack by microorganisms.

It has long been known that fungicidal and/or algicidal biocides areadded to plasters and paints in order to preserve films thereof. Thepurpose of this is to prevent unwanted infestation of the films bymicroorganisms, e.g., fungi, such as molds and yeasts, and also bybacteria, algae, and cyanobacteria (see D. Antoni-Zimmermann, P. Hahn,“Wässrige Siliconharz-Beschichtungssysteme für Fassaden” [Aqueoussilicone resin coating systems for facades], expert verlag, volume 522,pages 379 to 406). Such microorganism infestation occurs, for example,in the case of building facades provided with corresponding plasters andpaints. These facades discolor as a result of the growth of themicroorganisms and therefore require a new surface treatment after justa relatively short time, depending on the weathering situation.

On the one hand this affects those masonry coatings whose pH is in arange that allows the microorganisms to grow. The coating systems inquestion here are normally synthetic-resin-bound coating systems.

On the other hand, however, it also applies to silicate-bound plastersor paints. It is true that the pH of such systems is often in such ahigh range, owing to the high fraction of alkaline compounds, thatinitially there is no infestation by the microorganisms.Dispersion-based silicate coatings have a pH of from 11 to 11.5 whenapplied to a masonry construction. Pure silicate coatings orcementitious systems frequently have an even higher pH.

However, these high pH values subside over the course of time. Thisoccurs on the one hand owing to neutralization of alkaline constituentsof the coating material by atmospheric carbon dioxide. On the otherhand, however, there are apparently further causes of microorganisminfestation even in the case of strongly alkaline coatings. In recenttimes more and more cases have arisen in which, despite an alkalinecoating on building facades, overgrowth by algae or fungi, for example,occurs after just a relatively short time. One possible cause of thismight lie in the use of increasingly thicker or increasinglyhigher-quality heat insulation materials which are fitted to thebuilding facades beneath the coatings, partly as a consequence of newheat insulation provisions. The improved insulation reduces heatexchange between the interior of the building and the outer surface ofthe coating. This promotes condensation and retards the drying of theexterior coating (see J. P. Blaich, “Die Gebäudehülle” [The buildingshell], Fraunhofer IRB Verlag, pages 46 to 58, especially pages 48 to50, section 3, “Tauwasserniederschlag” [Condensation]).

The better the thermal insulation of a building facade the more quickly,and the greater the period of time, for which the temperature will fallbelow the dew point there. The consequence of this is the promotion ofleaching of alkaline constituents from the surface of the facade, whosepH consequently falls more rapidly into a relatively lower range, inwhich the plaster or the paint again allows microorganisms to grow. Atthe same time, owing to the relatively long moisture cycles, there isalso an increase in the extent of infestation.

EP 1108824 A1 discloses a building material comprising microcapsulescontaining hinokitiol as active substance. Said active substance isintended to emerge from the microcapsules over a prolonged period oftime and to spread within the building material in order thus toeliminate, for example, microbes and bacteria. Hinokitiol is inadequateas a biocide for specifically suppressing the growth of algae and fungion building facades to a sufficient extent.

EP 0758633 B1 describes porous granules which are loaded with chemicalsubstances in such a way as to act as a store for these substances andto release them slowly. An example of one such chemical substance is abiocide. The material of the granules can, for example, be a porousceramic material.

DE 432-4315 A1 reports on a final-coat plaster composition which canwhere appropriate include an added biocide. In no way, however, is thisbiocide protected from decomposition.

It is an object of the invention to specify a coating material, inparticular a plaster or paint, for protection against microorganisminfestation on surfaces exposed to the effects of damp or water. The aimhere is that microorganism infestation should be retarded or preventedeven when on the surface that is to be protected an initially high pHfalls in the course of time.

This object is achieved by the invention by means of a coating materialof the type specified at the outset which is characterized in that thecoating material comprises a biocide which is bound in a carriermaterial composed of particulate solids and is released retardedlytherefrom.

In accordance with a first embodiment the coating material of theinvention has a pH of at least 11. This has the advantage that,following application to the surface that is to be protected, thecoating material, by virtue of its alkaline-range pH, initially haltsthe growth of microorganisms, particularly of algae and fungi. A furtheradvantage is that when over the course of time, as a result of theeffect of atmospheric carbon dioxide and also of condensation andrainwater, the alkaline constituents of the coating material become moreand more neutralized and are leached from the coating material, and thepH of the material reduced as a result would allow microorganisms togrow again, the carrier material used in accordance with the inventiongradually releases the biocide it contains and so prevents furthergrowth of the microorganisms. All in all, therefore, the coatingmaterial maintains a flawless appearance of the surface that is to beprotected, and does so for a relatively long time. Absent the invention,a silicate-bound coating material, which by its nature has a relativelyhigh pH, could not be provided from the start with a biocide mixed in inthe usual way, since the biocide would be decomposed in the stronglyalkaline environment. Additionally, absent the invention, such a coatingmaterial would also lose its biocidal activity within a relatively shorttime, through leaching of the alkaline constituents, and would againallow algal or fungal growth.

In accordance with a second embodiment of the invention the coatingmaterial may also have a pH of well below 11.0, such as a pH of 8.5. Inthat case it is envisaged for application to a strongly alkalinesubstrate, e.g., to concrete or to the cement-bound reinforcing plasterof an exterior insulation and finishing system. In this case, alkalinecompounds gradually penetrate from the substrate material into thecoating containing the biocide, and as a result of the increase in pHwould normally decompose an unprotected biocide therein. This would bethe case, for example, if the coating were applied to the stronglyalkaline substrate before its pH had fallen, as a result of atmosphericcarbon dioxide, to a level at which the biocide remains stable. In thecase of isothiazolinones as active biocidal substances, for example, thepH would have to fall to about 4 to 9.

If in such a case, namely that of a strongly alkaline substrate, thebiocide were to be added to the coating in conventional manner, i.e.,without the particulate-solids carrier material used in accordance withthe invention, as is the case, for example, with knownsynthetic-resin-bound plasters and paints, the biocidal effect achievedwould be inadequate, or there would be none at all. The reason is thatthe strongly alkaline constituents penetrating the coating from thesubstrate decompose the biocide and/or convert it into a soluble form.The substances produced in this process no longer have a biocidal effectand/or are rapidly leached. Since only a few biocides with highstability in the strongly alkaline range are known, and in this range,therefore, the activity spectrum with respect to microorganisms isgreatly restricted, the invention provides a substantial improvement inthis respect.

The coating material of the invention is preferably a silicate-bound ormineral plaster having a pH of at least 11 or a synthetic-resin-bound orsilicone-resin-bound plaster having a pH of below 11.

In addition it is preferable for the coating material to be asilicate-bound paint having a pH of at least 11 or asynthetic-resin-bound or silicone-resin-bound paint having a pH of below11.

In accordance with the microorganisms which occur primarily in theenvironment of plasters and paints, it is preferred in accordance withthe invention for the biocide to be a fungicide, an algaecide or acombination of the two. It is also possible here to use more than twobiocides simultaneously.

Fungicides preferred in the context of the invention areisothiazolinones, carbamates, pyrithiones, aldehydes, ketones, quinones,amines, amidines, guanidines, hydrazo and azo compounds, aromaticcarbonitriles, carboxylic esters, carboxamides and carboximides,benzimidazoles, quinoxalines, imidazoles, triazoles, pyrimidines,triazines, halogenated and nitrated alcohols and phenols, perhaloalkylmercaptan derivatives, phosphoric and phosphonic esters,tetrahydro-1,3,5-thiadiazinethiones, thiocyanates and isothiocyanates,thiophenes, antibiotics, and active plant substances. Specific examplesof fungicides highly suitable in accordance with the invention aremethyl 1H-benzimidazol-2-ylcarbamate (carbendazim), 2-pyridinethiol1-oxide zinc (zinc pyrithione), 2-n-octylisothiazolin-3-one (OIT),4,5-dichloro-octylisothiazolin-3-one (DCOIT), and 3-iodo-2-propynylN-butylcarbamate (IPBC).

Algicides preferred in the context of the invention are triazines,N,N-dimethylureas, and uracils. Specific examples of algicides highlysuitable in accordance with the invention areN²-t-butyl-N⁴-ethyl-6-methylthio-1,3,5-triazine-2,4-diyldiamine(terbutryn), 2-chloro-4,6-bis(isopropylamino)-s-triazine,2-t-butylamino-4-ethylamino-6-methoxy-s-triazine,2-methylthio-4-butylamino-6-cyclopropylamino-s-triazine,4-butylamino-2-chloro-6-ethylamino-s-triazine,3-(4-isopropylphenyl)-1,1-dimethylurea,N′-(3,4-dichlorophenyl)-N,N-dimethylurea, and3-t-butyl-5-chloro-6-methyluracil.

The particulate solids of the carrier material are preferably granularparticles with cavities.

It is advantageous for these granular particles to be in the form ofmicrocapsules. Within these microcapsules the biocides are enclosed in afinely dispersed, liquid or solid phase. Suitable wall materials for themicrocapsules include a very wide variety of substances: natural,semisynthetic, and synthetic materials.

Natural materials preferred in the context of the invention for themicrocapsule walls are gum arabic, agar, agarose, maltodextrin, sodiumalginate, calcium alginate, dextran, fats, fatty acids, cetyl alcohol,milk solids, molasses, gelatine, gluten, albumin, shellac, starches,caseinates, stearins, sucrose, and also waxes, such as beeswax, carnaubawax, and spermaceti wax.

Preferred semisynthetic materials for the microcapsule walls arecellulose acetate, cellulose acetate butyrate, cellulose acetatephthalate, cellulose nitrate, ethylcellulose, hydroxypropylcellulose,hydroxypropylmethyl-cellulose, hydroxypropylmethylcellulose phthalate,methyl-cellulose, sodium carboxymethylcellulose, hydrogenated tallow,myristyl alcohol, glyceryl mono- or dipalmitate, hydrogenated castoroil, glyceryl mono- or tristearates, and 12-hydroxystearyl alcohol.

Preferred synthetic materials for the microcapsule walls areformaldehyde-melamine resins, acrylic polymers and copolymers, such aspolyacrylamide, polyalkyl cyanoacrylate, and poly(ethylene-vinylacetate), aluminum monostearate, carboxyvinyl polymers, polyamides,poly(methyl vinyl ether-maleic anhydride), poly(adipyl-L-lysine),polycarbonates, polyterephthalamide, poly(vinyl acetate phthalate),poly(terephthaloyl-L-lysine), polyaryl sulfones, poly(methylmethacrylate), poly(ε-caprolactone), polyvinylpyrrolidone,polydimethylsiloxane, polyoxyethylenes, polyesters, polyglycolic acid,polylactic acid and copolymers thereof, polyglutamic acid, polylysine,polystyrene, poly(styrene-acrylonitrile), polyimides, and polyvinylalcohol.

Particularly preferred microcapsule wall materials areformaldehyde-melamine resins. The microcapsule walls may also becomposed of two or more of the aforementioned materials.

There are numerous known methods of preparing the microcapsules used ascarrier material in the context of the invention (see, for example, C.A. Finch, R. Bodmeier, Microencapsulation, Ullmann's Encyclopedia ofIndustrial Chemistry, 6th Edition 2001, Electronic Release). Theappropriate method in each case can be selected in accordance with thedesired biocide and the microcapsule wall material to be employed.

It is also advantageous if the granular particles with cavities that areused are particles whose cavities are, for example, pores formed byfoaming of the material, as in the case of a foamed ceramic material orin the case of expanded clay, or if the cavities are structuralcavities, such as are present in zeolites.

Suitable granular particles in the form of a foamed ceramic material,and a variety of methods of preparing them, are known from EP 0758633B1, for example. Further carrier materials, such as zeolites, aredescribed in DE 4337844 A1.

The aforementioned particulate solids of the carrier material, e.g., asmicrocapsules, foamed ceramic material, zeolite, and the like,preferably have a size in the range from 30 to 40 μm.

In addition to the above-mentioned biocides and the materials for themicrocapsule walls or for the porous granules, the coating material ofthe invention may include any substances which are commonly known andconventional in dependence on the intended use of the material. Thisincludes, on the one hand, the corresponding binders and film formers,such as polyacrylates, polystyrene acrylates or silicone resins, and, onthe other hand, the known auxiliaries, such as pigments, fillers,solvents, thickeners, defoamers, plasticizers, dispersants, emulsifiers,and agents for adjusting the pH of the coating material.

The examples illustrate the invention.

Preparation Examples 1 to 3 illustrate the preparation of microcapsulesin which an active biocidal substance is enclosed.

Preparation Example 4 illustrates the preparation of a silicate-boundexterior plaster, Preparation Example 5 that of a synthetic-resin-boundfloat plaster.

Inventive Examples 1 to 4 and Comparative Examples 1 to 4 elucidate thesuperior stability of the plasters of the invention with respect toleaching of the biocide they contain.

Inventive Examples 5 and 6 and Comparative Examples 5 to 7 elucidate thegrowth of fungi on different plaster surfaces and the advantage achievedby the invention.

PREPARATION EXAMPLE 1

The substances indicated below were used to prepare microcapsulesenclosing zinc pyrithione (2-pyridinethiol 1-oxide zinc) as activebiocidal substance.

Substances used Amounts, g Water 389.6 Polyacrylate 1.5 (Coatex BR 3,Dimed) Gum arabic 0.6 Silicone defoamer 0.3 (Aspumit AP, Thor GmbH) Zincpyrithione powder 60.0 Concentrated hydrochloric acid 4.0Formaldehyde-melamine resin 144.0 (Quecodur DMQ, Thor GmbH) 600.0

For the preparation of the microcapsules the water was introduced first.Polyacrylate, gum arabic, silicone defoamer and the zinc pyrithione werestirred into the water. The resultant mixture was adjusted withhydrochloric acid to a pH of 3 and then heated to a temperature of 70°C. Subsequently the formaldehyde-melamine resin was added dropwise over1 h. The mixture was subsequently stirred at the same temperature for afurther 2 h.

The mixture obtained comprised the desired microcapsules and was usedunchanged in preparing the microcapsule plaster.

PREPARATION EXAMPLE 2

The substances indicated below were used to prepare microcapsulesenclosing DCOIT (4,5-dichloro-2-octylisothiazolin-3-one) as activebiocidal substance.

Substances used Amounts, g Water 389.6 Polyacrylate 1.5 (Coatex BR 3,Dimed) Gum arabic 0.6 Silicone defoamer 0.3 (Aspumit AP, Thor GmbH)DCOIT, 98% form 60.0 Concentrated hydrochloric acid 4.0Formaldehyde-melamine resin 144.0 (Quecodur DMQ, Thor GmbH) 600.0

For the preparation of the microcapsules the water was introduced first.Polyacrylate, gum arabic, silicone defoamer and the zinc pyrithione werestirred into the water. The resultant mixture was adjusted withhydrochloric acid to a pH of 3 and then heated to a temperature of 70°C. Subsequently the formaldehyde-melamine resin was added dropwise over1 h. The mixture was subsequently stirred at the same temperature for afurther 2 h.

The mixture obtained comprised the desired microcapsules and was usedunchanged in preparing the microcapsule plaster.

PREPARATION EXAMPLE 3

The substances indicated below were used to prepare microcapsulesenclosing IPBC (3-iodo-2-propynyl N-butylcarbamate) as active biocidalsubstance.

Substances used Amounts, g Water 338.4 Gum arabic 0.6 Silicone defoamer3.0 (Aspumit AP, Thor GmbH) IPBC, 50% aqueous 132.0 dispersion (ActicideIPW 50, Thor GmbH) Citric acid, 12% 60.0 Formaldehyde-melamine resin66.0 (Quecodur DMQ, Thor GmbH) 600.0

For the preparation of the microcapsules the water was introduced first.Polyacrylate, gum arabic, silicone defoamer and IPBC dispersion werestirred into the water. Subsequently the mixture was adjusted with thecitric acid to a pH of 1 to 2 and heated to a temperature of 55 to 60°C. Then the formaldehyde-melamine resin was added dropwise over 1 h.Subsequently the mixture was stirred at 55 to 60° C. for 2 h.

The mixture obtained comprised the desired microcapsules and was usedunchanged in preparing the microcapsule plaster.

PREPARATION EXAMPLE 4

A silicate-bound white exterior plaster with a grain size of 1.5 to 2 mmwas prepared. Prepared first of all was a premix, which was thenprocessed further to form a final mix, i.e., the plaster.

a) Premix

The following substances are mixed for 15 minutes in order to achieveintegration or dissolution.

% by weight Water 9.3 Dispersant (Sapetin D 20) 0.1 Silicate stabilizer(Betolin Quart 20) 0.3 Rheological additive (Rhodopol 50 MD) 0.1Titanium dioxide (Bayertitan R-KB-5) 3.0 Defoamer (TEGO-Foamex KS 10)0.2

The following substances are added with stirring to the mixtureobtained:

% by weight Styrene-acrylate copolymer dispersion, 6.0 50% by weight(Mowilith SDM 765 A) Al Mg silicate, D 50 300 μm 2.5 (Plastorit 05)Reinforcing fiber filler 0.5 (Arbocel B 400) Calcium carbonate, D 50 5μm 4.0 (Omyacarb 5-GU) Calcium carbonate, D 50 7 μm 5.0 (Omyacarb 10-GU)Calcium carbonate, D 50 23 μm 10.0 (Omyacarb 40-GU)

The following substances were added in succession with stirring to themixture obtained:

% by weight Hydrophobicizer 0.5 (TEGO Phobe 1040) Additive to preventsurface cracking 0.5 (Lubranil A 1520) Stabilized potassium silicate10.0 (waterglass, Betolin P 35, 29% by weight)

b) Final Mix

The premix indicated above under a) was aged for 3 days. Then thefollowing substances were mixed in with slow stirring:

% by weight Calcium carbonate, D 50, 160 μm 11.0 (Omyacarb 130-GU)Calcium carbonate grains, D 50 1200 μm 37.0 (Austro-tec 10/15)

The total amount of the quantities indicated above for the premix andthe final mix makes 100.0% by weight.

The finished final mix was the exterior plaster. The biocides were theneach mixed into this plaster in accordance with the examples below.

PREPARATION EXAMPLE 5

A synthetic-resin-bound white float plaster was prepared in conventionalmanner from the following substances.

% by weight Polyacrylate 13.2 (Acronal 290 D, BASF AG) Sodiumpolyphosphate, 0.8 25% strength solution Preservative 0.3 (Acticide MBS,Thor GmbH) Defoamer 0.3 (Agitan 280) Thickener, polyacrylate, 0.8 8%strength ammoniacal solution (Latekoll D, BASF AG) White spirit 1.0(180-210° C.) Butyl diglycol 1.0 Basophob WDS (BASF AG) 0.6 Titaniumdioxide, rutile 2.8 (Kronos 2044, Kronos Titan GmbH) Calcium carbonate39.5 (Omyacarb 40-GU) Calcium carbonate 25.5 (Omyacarb 130-GU) Al Mgsilicate 6.5 (Plastorit 05) Quartz shingle 4.5 Water 3.2 100.0

The float plaster obtained had a pH of from 8.5 to 9.

INVENTIVE EXAMPLE 1 AND COMPARATIVE EXAMPLE 1

The microcapsule-containing mixture of Preparation Example 1 was addedto the synthetic-resin-bound plaster obtained in Preparation Example 5,which has a pH of 8.5. The amount of biocide in the plaster was 578 ppm.

The plaster biocidally treated in this way was used to produce testspecimens in the form of plaster disks for the water storage tests. Forthis purpose the plaster was coated into a circular plastic mold havinga diameter of about 5 cm and a depth of 3 mm. The coat thicknesscorresponded to the grain size of the plaster. The plaster sample wasthen dried and fully cured. Thereafter the test specimen was removedfrom the mold and conditioned for the water storage test.

For comparison, plaster disks which differ from the above samples onlyin that the zinc pyrithione had been mixed into the plaster not inmicroencapsulated form but instead in normal powder form were produced.

For each sample, the amount of zinc pyrithione in the plaster before andafter water storage for various periods of time was measured.

The samples were subjected to static water storage in 1 l of DIBTsolution, the solution being replaced completely every 24 h with theexception of the 7th day.

The DIBT solution is an alkaline solution specified by the DeutschesInstitut für Bautechnik (DIBT) [German Institute of ConstructionEngineering] for the water storage of samples. The solution has a pH of12.5 and is composed of the following substances:

Sodium hydroxide 0.88 g Potassium hydroxide 3.45 g Calcium hydroxide0.48 g Water remainder to 1 l

The results are reported below.

Residual biocide in plaster (pH 8.5), ppm Storage in DIBT solution, daysNone 2 5 10 Inventive Example 1 578 478 259 187 Comparative 560 21 4 0Example 1

INVENTIVE EXAMPLE 2 AND COMPARATIVE EXAMPLE 2

Inventive Example 1 and Comparative Example 1 were repeated but with themodification that now the silicate-bound float plaster of PreparationExample 5, with a pH of 11.5, was used and storage in water took placefor 1, 2 and 7 days.

The results are reported below.

Residual biocide in plaster (pH 11.5), ppm Storage in water, days None 25 10 Inventive Example 2 531 423 325 21 Comparative Example 2 568 2 0 0

INVENTIVE EXAMPLE 3 AND COMPARATIVE EXAMPLE 3

Inventive Example 1 and Comparative Example 1 were essentially repeated,but with certain modifications. These were to the effect that, insteadof the zinc pyrithione microcapsules obtained in accordance withPreparation Example 1, the microcapsules containing DCOIT as activebiocidal substance, obtained in accordance with Preparation Example 2,were now used, and instead of water storage the samples were heated at atemperature of 54° C. for 4 weeks. The silicate-bound plaster ofPreparation Example 4 was used, with a pH of 11.5.

The results are reported below.

Residual biocide in plaster (pH 11.5), and biocide degradation afterheat treatment at 54° C. Heat treatment, ppm None 4 weeks Degradation, %Inventive Example 3 508 474 6.7 Comparative Example 3 521 382 26.7

INVENTIVE EXAMPLE 4 AND COMPARATIVE EXAMPLE 4

Inventive Example 3 and Comparative Example 3 were repeated, but withthe modification that instead of the microcapsules of PreparationExample 2, containing DCOIT, the microcapsules of Preparation Example 3,containing IPBC, were now used.

The results are reported below.

Residual biocide in plaster (pH 11.5), and biocide degradation afterheat treatment at 54° C. Heat treatment, ppm None 4 weeks Degradation, %Inventive Example 4 280 256 8.6 Comparative Example 4 291 211 27.5

INVENTIVE EXAMPLES 5 AND 6 AND COMPARATIVE EXAMPLES 5, 6 AND 7

Fungal growth on the sample surface was investigated.

The silicate-bound plaster of Preparation Example 4, applied to asupport plate, was either biocide-free (Comparative Example 5) or wasadmixed with 100 ppm of zinc pyrithione (Comparative Example 6), 200 ppmof zinc pyrithione (Comparative Example 7), 100 ppm of microencapsulatedzinc pyrithione (Inventive Example 5) or 200 ppm of microencapsulatedzinc pyrithione (Inventive Example 6).

The plaster samples were applied as a coat to calcium silicate plateswhich measured 4.5 cm×9 cm and have undergone water storage beforehand.The coat thickness of the plaster was within the order of magnitude ofits grain size, i.e., from 1.5 to 2 mm.

After the samples had cured, they were subjected to water storage as inInventive Example 1.

The test for fungal growth took place as follows:

The plaster samples were poured into a conventional agar nutrientmedium. Thereafter the samples were sprayed with a fungal sporesuspension. The suspension contained equal proportions of the followingtest organisms:

-   -   Alternaria alternata    -   Aspergillus niger    -   Cladosporium cladosporoides    -   Penicillium funiculosum    -   Ulocladium atrum

The total concentration of the fungal inoculum was 10⁶ spores/ml.

The samples were stored in the usual way over a relatively long periodof time under growth conditions optimum for fungi. Thereafter the fungalgrowth on the sample surface was evaluated.

The fungal growth on the sample surface was evaluated using thefollowing scale:

Growth rate Fungal growth 0 No growth visible x Minimal growth (up to25% surface coverage) xx Slight growth (up to 50% surface coverage) xxxModerate growth (up to 75% surface coverage) xxxx Severe growth (up to100% surface coverage)

The results of the fungal growth test for the samples investigated arereported below.

Fungal growth on the surface of the plaster (pH 11-12) without/with zincpyrithione Zinc pyrithione Water storage ppm None 2 days 5 daysComparative Example 5  0 xxx xxxx xxx Comparative Example 6 100 x x xxxComparative Example 7 200 0 x xx Inventive Example 5 100 (encapsulated)0 0 0 Inventive Example 6 200 (encapsulated) 0 0 0

1-12. (canceled)
 13. Biocide, bound in a carrier material composed ofparticulate solids, wherein the carrier material contains aformaldehyde-melamine resin and the biocide is zinc pyrithion,4,5-dichloro-2-octylisothiazolin-3-one, 3-iodo-2-propynylN-butylcarbamate, methyl 1H-benzimidazol-2-ylcarbamate, orN²-t-butyl-N⁴-ethyl-6-methylthio-1,3,5-triazin-2,4-diyldiamine or amixture of two or more of these compounds.
 14. Biocide according toclaim 13, wherein the particulate solids of the carrier material aregranular particles having cavities.
 15. Biocide according to claim 14,wherein the granular particles having cavities are microcapsules. 16.Biocide according to claim 13, wherein the wall material of themicrocapsules is composed primarily of a formaldehyde-melamine resin.17. Biocide according to claim 13, wherein the particulate solids have adiameter of from 30 to 40 μm.
 18. A method of protecting a coatingmaterial against microorganism infestation comprising the step ofincorporating a biocide according to claim 1 in said coating.